The subject invention is directed toward the art of web handling equipment and, more particularly, to an improved flotation nozzle design.
Systems for supporting and conveying a continuous moving web of material during processing such as drying, curing, baking, cooling or the like, typically comprise a multiple number of Coanda flotation nozzles positioned on opposite sides of the path of movement of the web. The nozzles are generally positioned along the entire span of floated web material in close proximity above and below the web. The nozzles direct air under considerable pressure through fixed slot openings which extend across the width of the web.
The typical prior art nozzle designs use a common air pressure chamber from which air is forced through at least two of the fixed slot type discharge openings on laterally opposite sides of the nozzle body to form an air pressure area at a Coanda surface of the nozzle between the discharge openings to thereby apply a force against the web of material traveling across the nozzle.
The flotation characteristics of the nozzles depend upon the uniformity of air flow through the nozzles and should desirably vary depending upon variations in the speed of movement of the web or when the type and weight of the web material changes. However, with the prior nozzle designs it has generally not been possible to maintain uniform flow throughout the length of the nozzles or to change the flotation characteristics of the individual nozzles. Thus, in any particular system, the ability to function efficiently at different web speeds or with different web materials was severely limited.